The invention relates to improvements to inflatable pneumatic boats comprising a rear board extending transversely and approximately vertically between two lateral floats.
In pneumatic boats of this kind, the rear board is simply a substantially flat board which extends between the two floats and is connected thereto in sealing-tight manner. The purpose of the rear board is to close the back of the boat and also to carry the outboard motor. It must therefore be sufficiently strong to withstand both the weight of the engine and the shocks transmitted by the engine during navigation on choppy water. From the point of view of mechanical strength alone, the flat shape normally adopted for the rear board is not the most suitable.
Also, the rear board overhangs the rear end of the bottom of the boat, and the propeller, which is carried by the engine secured to the rear board, rotates in a region where the water flow is particularly disturbed. This reduces its efficiency. Attempts have already been made to obviate this disadvantage by shifting the engine and propeller beyond the rear board so that the propeller can rotate in a region where the water flow is less disturbed. In that case, however, bulky accessories have to be positioned on the rear board and are expensive and increase the weight of the boat.
With regard to other considerations, some "composite-hull" inflatable boats have a rigid bottom surrounded by the inflatable float and a rigid deck structure attached to the rigid bottom and secured thereto along their common periphery. In this kind of boat, the rigid bottom and the rigid deck structure are both constructed with a rear panel extending approximately vertically upwards. When the bridge structure is fitted on the bottom, the vertical panel secured to the bottom faces the vertical panel secured to the bridge structure so as to form the rear board when connected. However, the bottom and the deck structure are assembled by sticking, and it is a difficult, lengthy process to position the two components and stick them correctly, since their shape is so complex. Also, the resulting rear board has insufficient mechanical strength and has to be reinforced. A plywood board, having substantially the same dimensions as the two panels joined to form the rear board, is inserted between the two panels. The wooden board is heavy and further increases the cost of the boat.
The main aim of the invention, as far as possible, is to obviate the various disadvantages of rear boards on conventional inflatable boats and to provide an improved rear board which is better at meeting the various practical requirements with regard to all the points previously mentioned and others also.